Steam-boiler-control system



Ot. 22, 1929. w. DOBLE STEAM BOILER CONTROL SYSTEM Filed Nov. 19. 1924-3 mount 01,

FIB-3 llll Warren Do/e lllll 4 I 2:- .Z: WW 0 0| Patented Oct. 22, 1929UNITED STATES PATENT OFFICE WARREN DOBLE, OF BERKELEY, CALIFORNIA,ASSIGNOR TO DOBLE STEAM MOTORS CORPORATION, OF WILMINGTON, DELAWARE, ACORPORATION OF DELAWARE STEAM-BOILER-CONTROL SYSTEM Application filedNovember 19, 1924. Serial No. 750,892.

The invention relates to a system for controlling the rate at whichWater is introduced into a steam boiler.

An object of the invention is to provide a system for varying the rateat which water is introduced into the boiler, in accordance with therate of steam consumption.

Another object of the invention is to provide a system for controllingthe amount of water introduced into the boiler in accordance with boilersteam temperature conditions.

A further object of the invention is to provide a system for controllingthe amount of heat added to the boiler in accordance with boiler steamtemperature conditions.

A further objectof the invention is to provide a boiler control systemin which an increase in temperature of the steam in the boiler causes anincrease in the amount of water introduced into the boiler, and afurther increase in temperature causes a decrease in the amount of heatadded to the boiler.

A further object of the invention is to provide an adjustable apparatuswhich operates automatically to control the rate at which water is'introduced into the boiler in accordance with the rate of steamconsumption.

The invention possesses other advantageous features, some of which, withthe foregoing, will be set forth at length in the following description,where I shall outline in full that form of my invention which I haveselected for illustration in the drawings aecompanying and forming partof the present specification. In said drawings I have shown one form ofapparatus embodying my invention, but it is to be understood that I donot limit myself to such form, since the invention, as set forth in theclaims, may be embodied in a plurality of forms.

Referring to said drawings:

Figure 1 is a diagrammatic representation of the system of my invention.

Figure 2 is a section through the device for controlling theintroduction of feed water into the boiler, in accordance with the rateof steam consumption and in accordance so with boiler steam temperature.

Figure 3 is a vertical section through the pum inlet.

The system of my invention comprises means for controlling the rate ofintroduction of feed water into the boiler in accordance with the rateof discharge of steam from the boiler. By such control, as the rate ofsteam consumption increases, the rate of introduction of feed waterincreases and vice versa, so that under normal conditions, the amount ofwater in the boiler remains substantially constant. Other factors beingequal, this control system operates to maintain a substantially constanttemperature within the boiler.

The invention also contemplates the provision of means whereby anincrease in boiler steam temperature, causes water to be intro ducedinto the boiler at a different rate, said rate being partiallycontrolled by said first mentioned control means. The invention furthercontemplates the provision of means whereby a further increase in boilersteam temperature to a predetermined maximum temperature will interruptthe supply of heat to the boiler. These various control devices areassociated with each other to pre vent the production of abnormalconditions of temperature Within the boiler. The feed water isintroduced into the boiler by a pump, which is preferably connected tothe engine, which is driven by steam from the boiler, so that theplunger of the pump is working when the engine is in operation and meansare provided whereby variations in temperature within the boiler andvariations in the rate at which the water pumped passes through anorifice control the operativeness of the pump to deliver water into theboiler. To control the amount of water introduced into the boiler, thepump is preferably disabled by controlling or preventing the operationof the pump inlet valve, so that re ciprocation of the pump piston willnot operate to pump water, as shown in my c0 vending application, SerialNo. 740,641, filed ept. 29, 1924, or by lay-passing a portion of thewater pumped back to the supply tank.

The rate at which water is introduced into the boiler is controlled bythe rate of the steam consumption and, by rate, I mean the number ofpounds of steam per minute or other time interval. The system isparticularly applicable to steam generating plants for use on steamautomobiles, conveyances or other vehicles in which the rate of steamconsumption is variable, due to varying opening of the throttle valve.In accordance with my invention the rate at which water is introducedinto the boiler varies in accordance with the rate at which steam isdischarged from the boiler and this rate is variable, due to conditionsof operation of the vehicle. The rate of steam consumption is measuredby passing the steam through a Venturi tube wherein the flow of steamproduces a high pressure zone and a low pressure zone, and thedifierential in pressure between the zones is employed to control therate at which water is introduced into the boiler. In steam propelledvehicle practice, the steam engine constitutes practically the entireload on the boiler, so that the rate at which water is introduced intothe boiler depends upon the rate at which the engine consumes steam.

The system comprises a boiler 2 which is supplied with heat by theburner 3, which is preferably a liquid fuel burner, operated by theelectric motor 4:. Usually the motor drives a blower 4 which produces inthe burner a spray of fuel and air. This combustible mixture is ignited,preferably by an electric spark, and the resultant flame is projectedinto the combustion space of the boiler. Means arecprovided for openingand closing the motor circuit in accordance with variations in thetemperature of steam in the boiler above and below a predeterminedmaximum value. Steam from the boiler is conducted through the pipe 5,which is provided with a throttle valve 5 to the steam engine 6, whichserves to drive the vehicle. Water is supplied to the boiler from thesupply tank 7 by a pumping mechanism 8 which usually comprises areciprocating pump having one or more cylinders. The pump is preferablydirectly connected to the steam engine by the shaft 12, so that when thesteam engine is in operation, the pump is driven. The water isdischarged from the pump and passes'through the pipe 13 to the controldevice 14, which will be described hereafter, and which controls therate at which water in introduced into the boiler and the operativenessof the pump to deliver water to the boiler. From the control device 14the water passes through the pipe 15 to the boiler.

The control device 14 is provided with means for controlling the rate atwhich water is introduced into the boiler in accordance with the rate atwhich steam is discharged from the boiler, with means operative by anincrease in boiler steam temperature to a predetermined value forvarying the rate to permit water to be introduced into the boiler at agreater rate and with means operated by variations in the rate at whichthe Water passes through an orifice to control the operativeness of thepump. The device comprises a casing having passages or conduits thereinthrough which the water passes and having control devices forcontrolling the passage of such water through said conduit and havingdisplacement operated devices for con trolling the operativeness of thepump. The water discharged by the pump passes through the pipe 13 to theinlet conduit 17 in the device 14 and the water discharges from the device through the outlet conduit 18 into the pipe 15, which is connectedto the boiler. The conduit 17 is connected to the conduit 18 bv thepassage 19 and means are provided for controlling the rate at whichwater passes through the conduit 19. The passage of water through thisconduit is controlled by the valve 21, secured to the valve stem 22which is attached to the piston 23 disposed in the cylinder 24. Theopening movement of the valve 21 is opposed by a spring 25 disposed inthe cylinder above the piston, the spring being light and being inactivewhen the valve 21 is closed on its seat. The area of the opening betweenthe valve 21 and its seat is less than the area of the passageway 19, sothat such opening constitutes an orifice or restricted passage throughwhich the water nor mally passes to the pump. In order to force waterthrough the orifice, the pressure in the passage 19 must be greater thanthe pressure in the passage 18, and, with an orifice of constant area,the greater the diiiercntial pressure on opposite sides of the orifice,the greater will be the rate at which water will fiow through theorifice. It is also manifest that, the pressure remaining substantiallyconstant, a variation in the area of the orifice will cause a variationin the rate at which water flows through the orifice.

Means are provided for varying the position of the piston 23 inaccordance with the rate at which steam is discharged from the boiler.Arranged in the conduit 5 through which the steam discharges, is aVenturi tube 26 in which high pressure and low pressure zones areproduced by the difierent velocities of the steam at diiferent parts ofthe tube. The high pressure zone of the Venturi tube 26 is connected tothe cylinder 24 below the piston 23 therein by the conduit 27, so thatthe high pressure is effective on the under Side of the piston. The lowpressure zone of the Venturi tube is connected to the cylinder 24 abovethe piston 23 therein by the conduit 28, so that the low pressure iseffective on the upper side of the piston. The piston is thereforesubjected to a diiferential pressure, the magnitude of which varies withthe velocity of steam through the tube 26 and this varying differentialpressure causes a variation in the position of the piston 23 andconsequently a variation in the position of thev Valve 21 and avariation in the size of the orifice. As the velocity of the steamincreases, this diiferential increases and causes the valve 21 to bemoved to increase the area of the orifice and conse uently increase therate at which water is introduced into the boiler. Conversel a decreasein the velocity of the discharging steam causes a decrease in the rateat which water is introduced into the boiler.

Since the pump is directly connected to the engineand since the speed ofthe engine is variable and since the speed of the engine is notdependent upon the rate of steam consumption, due to varying loads onthe engine, means are provided for controlling the amount of waterpumped in accordance with the requirements of the boiler. This meanspreferably comprises means .for enabling or disabling the pump todeliver water to the boiler so that the amount of water pumped may bevaried regardless of the speed of the engine. The control of thequantity of water delivered by the pump mechanism is preferablyaccomplished by controlling one of the pump valves and since the inletvalve operates under less pressure than the discharge 'valve, I preferto control the operation of the inlet valve. The pump is provided withan inlet valve 31, which is preferably guided in' the pump inlet 32 byvanes on the underside of the valve which extend into the inlet conduit.If this valve is held unseated, the reciprocation of the piston in thepump will not operate to pump water. Means are provided for holding thevalve unseated when it is (18 sired to disable the pump. Arranged belowthe inlet conduit is a housing 33 in which there is disposed a solenoid34. Disposed within the solenoid is a core 35 having a stem 36 extendinginto the inlet conduit and terminating adjacent the under side of thevalve 31. The core 35 is provided on its under side with a stem 37 whichis surrounded by a spring 38 which tends to move the core 35 upward tohold the valve 21 from its seat,

thereby disabling the pump. The solenoid circuitis normall closed andthe solenoid thus normally ho ds the core 35 in its depressed position,holding the stem 35 from engagement with the valve31 so that the valveis free to operate, thus enabling the pump. When the solenoid circuit isopened, the spring 38 moves the stem 36 upward and holds the inlet valve31 from its seat so that :the pump is then disabled and renderedinopdetermined magnitude, the solenoid circuit is opened and the pumpdisabled; the reverse subsequently occurring when the pressuredifference decreases to a predetermined magnitude. Connected in serieswith the solenoid 34 is a source of electrical energy such as thestorage battery 43 and a main switch 44. The solenoid circuit is alsoprovided with a differential pressure actuated switch which is openedwhen the difl'erential pressure on opposite sides of the orifice reachesa predetermined magnitude. Arranged in the casing 14 is a cylinder 46 inwhich is disposed a piston 47 which is loaded on its upper side with aspring 48, the pressure of which is adjustable by the screw 49. Theinlet eonduit 17 opens into the cylinder 46 on the under side of thepiston, so that the piston is subjected on its under side to thepressure in the conduit 17 and the outlet conduit 18 is connected to thecylinder 46 on the upper side of the piston, so that the piston issubjected on its upper side to the pressure in the conduit 18, plus thepressure of the spring 48. The piston 47 is thus moved to variablepositions, depending upon the magnitude of the diiferential pressure atopposite sides of the orifice or depending upon the difference betweenthe rate at which water is pumped and the rate at which it passes theorifice. Connected to the piston 47 is a lever 51 which extends to theoutside of the casing and which has its outer movable end disposed inclose relation to one end of the switch lever 52. Upward movement of thepiston 47 due to an increase in the diiierential pressure to apredetermined magnitude, causes the lever 51 to rock the switch lever 52and open the solenoid circuit at the switch 53, thus disabling the pump8. Conversely, when the differential pressure decreases to apredetermined minimum, due to the disabling of the pump, the switch 53is' again closed and the pump 8 enabled to deliver water under pressureto the casing 14. Durin the operation of the pump, the pressure of thewater pulsates, due to the reciprocation of the pump plunger, and the piten 47 moves to compensate for the pulsations. The cylinder 46 hassuflicient volume to act as a pressure storage chamber, into and out ofwhich water flows as the dili'erential pressure at the orifice varies.

The control device 14 also embodies means for controlling theintroduction of water into the boiler in accordance with boiler steamtemperature conditions. The conduit 17 is connected to the conduit 18 bya second passage 55 which constitutes a by-pass of the conduit 19. Theinlet to the conduit 55 isnormally closed by the valve 56 in contactwith the inlet end of the conduit 55. The amount of water which may theconduit 55 is controlled by the-adjustable valve 57 associated with thedischarge end of the conduit 55. The stem of the valve valve 21 lies inthe cinduit 18 and the valve 57 extends into the conduit 18 but thesizes of the stems of these valves are such as not to interfere with thepassage of water through the conduits 17 and 18, so that the presence ofthese valves does not interfere with the passage of water to thecylinder 46.

Means are provided for controlling the position of the valve 56 inaccordance with temperature conditions within the boiler and these meansare so arranged that when the temperature within the boiler reaches acertain predetermined magnitude, for instance, 750 F., the valve 56 isoperated to open the conduit 55 and thereby permit the feed water topass from the conduit 17 to the conduit 18. Secured to the stem of thevalve 56 is a core 54 which is normally pressed upwardby a spring 58 toseat the valve. Surrounding the core 54 is a solenoid 59 which, whenenergized, draws the core 54 downward and opens the conduit 55. Thecircuit of the solenoid 59 is connected across the battery 43 and themain switch 44 and includes a switch which is actuated when thepredetermined temperature is reached in the boiler, to close thesolenoid circuit. Normally, the solenoid circuit is open. The switch inthe circuit of the solenoid 59 is operated by a suitable thermalresponsive device suchas the quartz rod 61 which is disposed within ametallic tube fixed at one end to the shell of the boiler and extendinginto the steam space in the boiler. As the temperature of the steam inthe boiler increases, the metallic tube is elongated and the quartz rodrecedes and efiects the closing of the switch. The switch comprises aswitch arm or lever 62 fulcrumed at one end to a suitable bracket andpivoted to the quartz rod 61. This lever carriesa contact 63 which, asthe lever moves downwardly due to the expansion of the metallic tube,contacts with the yieldingly mounted contact 64, thus closing thesolenoid circuit and opening the valve 56. The switch arm 62 is adjustedto cause the circuit to be closed at a definite predeterminedtemperature, for instance, 7 50 F.

.VVhen this temperature is reached the solenoid circuit isvclosed andthe water is bypassed around the rate controlling device and when thetemperature within the boiler again drops the switch is opened and thevalve 56 again closed.

Means are also provided for interrupting the supply of heat to theboiler in accordance with boiler steam temperature. Arranged in serieswith the circuit of the motor 4 which drives the blower, is a switchcomprising the switch arm 62. and the contact 65. The contact 63 on theswitch armis normally in engagement with the contact 65 so that thecircuit through the motor is closed when the main switch 44 is closed.When the temperature within the boiler reaches a predetermined maximumwhich may be between 900 and 1200 F. the contact 63 moves fromengagementwith the fixed contact 65, thus opening the motor circuit andinterrupting the supply of heat to the boiler. As the temperaturesubsequently drops and the arm 62 is moved upward, the motor circuit isagain closed and heat is again supplied to the boiler.

I claim:

1. The combination with a steam boiler of a continuously operated pumpfor introducing water into the boiler, a valve for controlling the flowof water into the boiler, means controlled by the volume of steamdischarging from the boiler for controlling the area of the valveopening and means actuated by an increase in differential pressure atopposite sides of the valve opening to a predetermined magnitude forcontrolling the water pressure on the pump side of the valve.

2. The combination with a steam boiler of a pump for introducing waterinto said boiler, means controlled by the passage of steam from theboiler for controlling the rate at which water is introduced into theboiler and means operated by the difference in pressure on oppositesides of said controlling means for controlling the introduction ofwater into the boiler.

3. The combinationwith a steam boiler of a pump for introducing waterinto said boiler, means controlled by the passage of steam from theboiler for controlling the rate at which water is introduced into theboiler and means operated by variations in the dill'ercnce in pressureon opposite sides of the control means for enabling and disabling thepump.

4. The combination with a steam boiler of a pump for introducing waterinto said boiler. means controlled by the rate of discharge of steamfrom the boiler for controlling the rate at which water is introducedinto the boiler and coacting means connected in parallel with said firstmeans and controlled by the temperature of the steam in the boiler forcontrolling the introduction of water into the boiler.

5. The combination with a steam boiler of a pump for introducing waterinto said boiler, means controlled by the rate of discharge of steamfrom the boiler for controlling the rate at which water is introducedinto the boiler and coacting means connected in parallel with said firstmeans and controlled by an increase in the temperature of the steam inthe boiler to a predetermined magnitude, for increasing the rate atwhich water is introduced into the boiler.

6. The combination with a steam boiler of a pump for introducing waterinto said boiler. means controlled by the rate of discharge of steamfrom the boiler for controlling the rate at which water is introducedinto the boiler and means controlled by an increase in the tem eratureof the steam in the boiler to a pre etermined temperature for augmenting4 said first named control means in controlling the rate at which wateris introduced into the boiler.

7. The combination with a steam boiler of a pump for introducingwaterinto said boiler,

. means controlled by therate of discharge of water around'said firstnamed control means.

8. The combination with a steam boiler of a pum for introducing waterintosaid boiler, a con uit connecting said pump and boiler, a valve insaid conduit, means controlled by the passage of steam'from the boilerfor varying the position of said valve and coacting means connected inparallel with said first means and controlled by the temperature of thesteam in the boiler for controlling the introduction of water into theboiler.

9. The combination with a steam boiler of a pump for introducing waterinto said boiler, a conduit connecting said pump and boiler, a valve insaid conduit, means controlled by the passage of steam from the boilerfor varying the position of said .valve and means controlled by anincrease in the temperature of the steam in the boiler to a predetermined temperature for augmenting said valve in controlling the rateat which water is introduced into the boiler.

10. The combination with a steam boiler of a pump for introducing waterinto said boiler, a conduit connecting said pump and boiler, a valve insaid conduit, means controlled by the passage of steam from the boilerfor varying the position of said valve and means controlled by anincrease in the temperature of the steam in the boiler to apredetermined temperature for by-passing the water around said valve.

11. The combination with a steam boiler of a pump-for introducing waterinto said boiler, a conduit connecting said pump and boiler, a valve insaid conduit, means controlled by the passage of steam from the boilerfor varying the position of said valve and means controlled by thedifference in pressure on opposite sides of the valve for controllingthe introduction of water into the boiler.

12. The combination with a steam boiler of a pump for introducing waterinto said boiler, a conduit connecting said pump and boiler, a valve insaid conduit, means controlled by the passage of steam from the boilerfor varying the position of said valve and means controlled by thediiierence in pressure on opposite sides of the valve for controllingthe operation of the pump.

13. The combination with a steam boiler of a pump for introducing waterinto sa1d boiler, a conduit connecting said pump and boiler, a valve insaid conduit, means controlled by the passage of steam from the boilerfor varying the position of'said valveand means controlled by thedifference in pressure on opposite sides of the valve for enabling anddisabling the ump.

14:. The combination wit a steam boilerv of a pump having a valve forintroducing water into said boiler, a conduit connecting said pump andboiler, a valve in said conduit, means controlled by the passage ofsteam from the boiler for varying the position of said valve and meanscontrolled by the difference in pressure on opposite sides of the valvefor controlling the operation of said pump valve.

15. The combination with a steam boiler of a pump for introducing waterinto the boiler, a conduit connecting said pump and boiler, a valve insaid-conduit, means controlled by the passage of steam from the boilerfor varying the position of said valve,

a by-pass conduit connecting the pump to the boiler around said valve, asecond valve nor mally closing the by-pass conduit and means actuated byan increase in boiler steam temperatureto a predetermined temperaturefor unseating said second valve to open the bypass conduit.

16. The combination with a steam boiler of a pump for introducing Waterinto the boiler, a conduit connecting said pump and boiler, a valve insaid conduit, means controlled by the passage of steam from the boilerfor varying the position of said valve, a. by-pass conduit connectingthe pump to the boiler around said valve, a second valve normallyclosing the by-pass conduit, a solenoid for moving said second valve toopen the by-pass conduit, a circuit for said sole noid and meansactuated by an increase in boiler steam temperature to a predeterminedtemperature for closing said solenoid circuit.

17! The combination with a steam boiler, an engine connected thereto andconstituting substantially the entire load on said boiler, a feed waterpump connected to said engine, means controlled by the rate at whichsteam flows to the engine for controlling the rate at which the feedwater is introduced into the boiler and means controlled by the steamtemperature within the boiler for augmenting said first control means incontrolling the rate at which water is introduced into the boiler.

18. The combination with a steam boiler, an engine connected thereto andconstituting substantially the entire load on said boiler, a feed waterpump connected to said engine, means controlled by the rate at whichsteam flows to the engine for controlling the rate at which the feedwater is introduced into the boiler and means actuated by the differencein pressure on opposite sides of the control means for controlling theoperation of the pump.

19. The combination with a steam boiler,

an engine connected thereto and constituting substantially theentire'load on said boiler, a feed water, pump connected to said engine,means controlled by the rate at which steam flows to the engine forcontrolling the rate at which the feed water is'introduced into theboiler, means controlled by the steam temperature'within the boiler foraugmenting said first control means in controlling the rate at whichwater-is introduced into the boiler and means actuated by the differencein pressure on opposite sides of said first control means forcontrolling the operation of the pump.

20. The combination with a steam boiler and an engine connected thereto,of a feed water pump connected to the engine, a conduit connecting thepump with the boiler,

means for controlling the rate of fiowof water through the conduit inaccordance with the rate atwhich steam discharges from the boiler andmeans controlled by boiler steam temperature for by-passing waterarou'nd'said control means.

21. The combination with a steam boiler and an engine connected thereto,of a feed water pump connected to the engine, a conduit connecting thepump with the boiler, means for controlling the rate of flow of waterthrough the conduit inaccordance with 'thetrate at which steamdischarges from the boiler, means controlled by boiler steam temperaturefor by-passing water around said control means and means for controllingthe rate at which water passes through said by-pass.

22. The combination with a steam boiler of a pump for introducing waterinto said boiler, a conduit having a restricted passage thereininterposed between the pump and the boiler, means controlled by thedifference between the rate at which Water is pumped and the rate atwhich it passes through the passage for controlling the operation of thepump and means controlled by variations in the rate of discharge ofsteam from the boiler for varying the area of the passage.

23. Regulating means for a steam boiler comprising a casing having aninlet passage,

an outlet passage, two conduits connecting said inlet and outletpassages, means connecting said inlet and outlet passages, meansresponsive to the velocity of steam discharged from said boiler forobstructing one of said conduits, means responsive to the my hand.

WARREN DOBLE.

temperature of the steam in said boiler for obstructing the otherof-said conduits, and

means responsive to differential pressure in said inlet and outletpassages for regulating the pressure in said inlet passage.

24. The combination of a steam boiler, a pump for introducing Water intosaid

